question: what gearing?
12-15-2002, 07:52 PM
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question: what gearing? say a car making 420 rwhp peak at 7,200 rpm, running 26x10 slicks ... what gearing would you choose? Maximize 60' and ET, mph is not important.
12-15-2002, 09:46 PM
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Re: question: what gearing? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Bob Cosby:
<strong>What does the car weigh?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">With him in it,,,,,, A LOT!!!!!!!!
Jaba, I would stick 4.30's in there.
MPH is STILL important.
Tim
<strong>What does the car weigh?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">With him in it,,,,,, A LOT!!!!!!!!
Jaba, I would stick 4.30's in there.
MPH is STILL important.
Tim
12-15-2002, 10:13 PM
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Re: question: what gearing? Ok. Assuming you want to optimize ET (as you said) and can rev the car to whatever rpm you need to, then you'd likely want something near 4.88's.
Reasoning:
1) 420 RWHP @ 3700 lbs should be 117-119 mph trap.
2) Optimizing ET, you typically want to go through the traps several hundred rpm above peak. That means with a 7200 rpm peak, you need to grow somewhere on the far side of 7500.
3) Heavy cars need lots of gear.
4) 4.88's still would only put you around 7500 through the traps, but I figure that is about the limit most would go to.
Reasoning:
1) 420 RWHP @ 3700 lbs should be 117-119 mph trap.
2) Optimizing ET, you typically want to go through the traps several hundred rpm above peak. That means with a 7200 rpm peak, you need to grow somewhere on the far side of 7500.
3) Heavy cars need lots of gear.
4) 4.88's still would only put you around 7500 through the traps, but I figure that is about the limit most would go to.
12-16-2002, 08:04 AM
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Re: question: what gearing? I like the 4.88 idea also but this comes from a nut that runs 5.13's in his Hot Rod. <img border="0" alt="[devil]" title="" src="graemlins/gr_devil.gif" />
Thinking about going to 5.38's over the winter. <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />
Thinking about going to 5.38's over the winter. <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />
12-16-2002, 10:11 AM
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Re: question: what gearing? As I increase the rpm potential of my motor, I am becoming more and more under-geared, even with the 4.56's. I've thought about stepping up to 4.88's when I get the T5 (it will have a .59 OD vs the .67 I have now), but I'm mostly worried about strength. There has to come a point at which those tall gears start to get weak, don't you think?
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12-16-2002, 01:04 PM
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Re: question: what gearing? I ran the calculator for the 4:30's, but I think I could use more gear. My fear is that a taller gear would hurt on the launch by blowing the tires away with the higher rpm launch.